Dear JP,
So 2-segment segmented EPI - yes your effective TR is 2x the 'TR' given for
each shot.
You would expect some other timing-related effects, you might need to
consider temporal and dispersion derivatives to account for any changes to
to the response shape from combining the data from different times.
David
______________________________________
David Carmichael PhD MInstP
Senior Research Fellow in MR Physics
Department of Clinical and Experimental Epilepsy
UCL Institute of Neurology
Correspondence to:
Advanced Magnetic Resonance Imaging Group
12 Queen Square
London WC1N 3AR
Tel +44 (0)20 76762006
Fax +44 (0)20 76762005
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-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On
Behalf Of JP
Sent: 07 January 2010 13:10
To: [log in to unmask]
Subject: [SPM] Two-shot EPI - Half the duration of the session
Hello,
We are analyzing for the first time 2-shot EPI data of a functional session
that lasted approx. 24 min. However, when the images are reconstructed, only
half that time is represented, i.e. the time plot stops at around 12min.
We understand that we have 1 image every 2 TRs (or 1 shot per TR), so is the
right/best way to analyze these data (and see our entire 24-min timeline) to
manually change the TR to double its actual value? How else can we proceed?
Thank you for any pointers!
J
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